In some display screen technologies, such as liquid crystal display (LCD), a pixel array is overlaid with a common electrode plane, e.g., a Vcom plane, which consists of a number of conductive lines, each of which run horizontally next to a row of adjacent pixels. The pixels of a row are electrically connected to an adjacent Vcom line. The Vcom line is driven by a pixel compensation circuit, which is designed to control the voltage on the Vcom line in such a manner that helps compensate for a so-called pixel kickback voltage, during row-by-row scanning of the pixel array for purposes of displaying an image. This may help reduce flicker on the display screen.
In certain touch sensing display screen (touchscreen) technologies, the Vcom line is dual-purposed; during a display interval, the Vcom line is driven by a pixel compensation (to improve the accuracy of the display screen function), while during a blanking interval (also referred to as a touch interval), the Vcom line is driven by touch sensing circuit, e.g., a capacitive touch stimulus or detection circuit. The display and touch intervals repeat at a suitable refresh rate, while the display screen is active, i.e., turned on.